1. Field of Invention
The present invention is directed to a device for imaging a gem, and more specifically, a device capable of imaging the fire of a gem and thereby enabling the qualitative assessment of the fire of the gem.
2. Description of the Related Art
For purposes of this invention, the term “gem” or “gems” will be used to describe gemstones, diamonds, minerals, rocks, petrified material, amber, manufactured gems, stone, and any other solid transparent or translucent material capable of refracting and dispersing light.
There are four commonly recognized quality factors of gems, and specifically, of diamonds. These four quality factors, commonly referred to as “color,” “clarity,” “carat,” and “cut,” were promoted by the DeBeers Diamond Company starting in 1948. Today, these four quality factors are used by both consumers and the gemological industry to appraise the value of a gem.
For example, the “color” of a diamond is usually rated on a color-grading scale, which ranges from D (colorless) to Z (light yellow). The color-grading scale is used by comparing a diamond with pre-graded comparison stones. For example, while colorless diamonds are widely considered the most rare and expensive, most jewelry diamonds are nearly colorless or have a faint touch of yellow.
“Clarity” relates to the flawlessness of a gem. Generally, for example, a diamond is categorized in six broad grading categories: (i) flawless, commonly referred to as “F”, (ii) internally flawless, commonly referred to as “IF”, (iii) very, very slightly included, commonly referred to as VVS1 and VVS2, (iv) very slightly included, commonly referred to as VS1 and VS2, (v) slightly included, commonly referred to as SI1 and SI2, or (vi) included, commonly referred to as either I1, I2, or I3. Categorizations are usually based on examination of gems with a binocular microscope at 10×. IF gems, are considered the most rare and the most expensive of all gems.
The term “carat” indicates the weight of a gem. A carat is equal to 200 milligrams and is divided into 100 points. Gems of one carat or more are generally considered more rare, and generally, the cost of the gem increases along with the carat weight.
The final quality factor is “cut.” Cut refers not only to the shape of the gem, but also to its proportions, symmetry and polish. Some skilled in the art believe that the quality of the cut is primarily responsible for making a gem appear brilliant and colorful, or in the alternative, dull and lifeless.
The most widely used standards for grading the cut of a diamond are those of the American Gem Society (hereinafter referred to as the “AGS”). The AGS system rates a diamond's cut according to proportions, symmetry and polish. The AGS grading systems generally rank diamonds from zero (0) to ten (10), with zero (0) being the highest in each category. Diamonds that achieve zero scores in the proportions, symmetry and polish categories are commonly called “Triple Zeros” in the industry.
However, even an ideally cut gem can still fail what is often considered the most important element of gem beauty: maximum fire. Fire is defined as the colored rays of light arising due to the dispersion of light through a gem. A gem with maximum fire will reflect a significant amount of available light from the gem to a viewer's eye, thereby revealing the fire of all the colors in the spectrum. There are two common types of fire: broadflash or pinfire. The type of fire reflected to a viewer is determined by the viewer's overall ability to see the fire in a typically complex illumination environment. A gem is considered to exhibit broadflash fire when whole facets of the gem exhibit the same purer spectral hue. Broadflash fire is considered to be superior to pinfire fire, wherein a gem returns a constant color in much smaller areas. It is more difficult, if not impossible, for a viewer to resolve the fire of a gem when the constant color is located in a smaller area.
A purchaser of a gem is likely to be interested in assessing the four quality factors of a gem, as well as the fire of the gem. This assessment will preferably occur prior to the purchase of the gem. Thus, the gemological industry has created a number of instruments capable of assessing various quality attributes of a gem.
For example, U.S. Pat. No. 3,867,032 assigned to Diharo Diamanten Handels Compagnie Establishment, and entitled Arrangement for Objectively Evaluating Characteristics of Gems, Particularly Diamonds (the “'032 Patent”), discloses a device that is specifically designed to provide an arrangement for evaluating cut gems, especially diamonds. The '032 Patent discloses an arrangement wherein a diamond is located at the bottom of an ellipsoidal housing. The ellipsoidal housing has an interior surface, a portion of which is formed as an ellipsoidal mirror. Light emitted from the end of a fiber optic element into the top of the ellipsoidal housing is shown into the diamond. The brilliance of the diamond is measured by placing photocells both below the diamond and at the top of the ellipsoidal housing. According to the '032 Patent, an ideal diamond will reflect light out of the upper portion of the diamond. A less than ideal diamond will either absorb the light or allow it to pass through to the photocells located directly below the diamond.
Another example of a gem assessing device may be found in U.S. Pat. No. 5,196,966, assigned to Massayo Yamashita, entitled Method and Implement for Observing or Photographing Gems such as a Diamond (the “'966 Patent”). This implement is specifically designed to permit one to precisely know the degree of the brilliance of a diamond, the colors of the light, and so on. The implement, as disclosed in the '966 Patent, is generally comprised of a base with a cylindrical container set on top of the base. A diamond is placed inside the container. Located at the top of the container is a surface that has a hole through which a camera or other viewing device may be positioned in order to photograph or view the diamond. In use, either natural light or an illuminating device reflects light either: (a) directly into the container to the diamond; or (b) against the base, up against the surface and into the container to the diamond.
A further example of a gem assessing device may be found in U.S. Pat. No. 5,260,763, assigned to Massayo Yamashita, entitled Instrument for Observing Jewels' Brilliance as Diamond, and Method of Taking Photographs with Said Instrument (the “'763 Patent”). The instrument is specifically designed to observe the brilliance of jewels, especially of diamonds, and a method of photographing them with this instrument. Essentially, the instrument includes a tubular vessel comprised of elements such as a lower tubular portion that does not permit the passage of light (or alternatively, is chromatic as red) and an upper tubular portion which is semi-transparent. The semi-transparent nature of the upper tubular portion limits and makes uniform the light entering the tubular vessel and into a diamond. The upper tubular portion may be reshaped to adjust the entering light volume. Further, a black cloth may be placed between the upper tubular portion and lower tubular portion to lessen the light entering into the diamond.
While the devices set forth in the '032 Patent, '966 Patent, and '763 Patent assess certain attributes of a diamond, there is currently a need in the gemological industry for a device capable of capturing an image of the fire of a gem in a qualitatively repeatable manner.